Safety lock for electric bulbs



Sept. ll, 1923.

J. W. DOWARD SAFETY Loox FOR ELECTRIC BULBS Filed septv. 4, 1920 Anm/wy Patented Sept. 11, 1923.

JAMES WILLIAM DOWARD, OF HALIFAX, NOVA SCOTIA, CANADA.

SAFETY LOCK FOR ELECTRIC BULBS.

Application filed September 4, 1920. Serial No. 408,281.

To all 'whom it may @011.06m

Be it known that I, JAMES WILLIAM DOWARD, a citizen of the Dominion of Canada, residing at Halifax, in the county of Halifax and Province of Nova Scotia,

have invented certain new and useful Improvements in Safety Locks for Electric Bulbs, of which the following is a specification.

This invention relates to improvements in safety locks for tungsten and other electric bulbs, commonly used on lighting systems. In publicl places, factories, warehouses, and other places, a considerable number of electric bulbs are misappropriated and the financial loss is considerable, besides which the inconvenience occasioned by the loss, and the loss of time and expense in having to replace the globes is considerable.

The principal object of my invention is to lock the lamp within the socket in such a manner that if any one attempts to remove the lamp or bulb, it will become broken and unfit for service.

It is also the object of my invention, to construct this locking feature in a very simple manner, so that it can be applied to standard sockets, and with the bulbs or lamps engaging therewith.

So that the nature of my invention will be properly understood, I have illustrated a preferred embodiment of the same which will now be described, after which the novel features will be pointed out in the appended claim.

In the drawings Figure 1 is a view of a bulb or lamp embodying my invention and showing the socket with which the lamp engages in section.

Figure 2 is a perspective view of the top of the lamp and a portion of the socket, showing my improved locking means.

Figure 3 is a cross section through the socket above the top of the lamp showing the central contact of the lamp and a portion of the locking means formed of electrically nonconducting material.

Figure 4c is a view of a lamp or bulb being threaded into a socket and showing the locking means automatically adjusting itself to lock the lamp or bulb within the socket. The

same symbols are used to indicate corresponding parts in the figures.

Referring to the drawings A indicates an ordinary lamp socket, and B a lamp or bulb which is threaded into the socket.

In the socket A, the threaded sleeve 1 forms one terminal and a central terminal 2 is provided, and one of the wires 3 in the bulb or lamp is connected with a central contact 4; of the lamp, while the other wire 5 is connected to the metallic threaded ferrule 6 of the bulb or lamp.

This construction is all well known with ordinary lighting system sockets, and electric bulbs or lamps.

To prevent the lamp being stolen from the socket A, I provide a pair of spring lingers 7, which are secured to the threaded sleeve 1, and the free ends of the springs are offset and extend inwardly towards the centre of the socket A. Y

On the lamp B, I provide a locln'ng flange or disc 8 which is secured to the threaded end of the lamp and is formed of an elec- .trically non-conducting material. This flange will be also connected to the central contact 4 of the globe or lamp.

When the globe or lamp B is being threaded into the socket A, the spring fingers 7 80 will be laterally displaced by the locking flange 8, but after the locking flangepasses the ends of the lingers they willspring back, and engage with the under face of the iiange.

Any attempt to remove the bulb or lamp B will now result in the flange 8 being broken and the breaking yof this flange will also break the contact 4; and destroy the lamp.

The lamp cannot therefore be removed until it is burned out, without being broken, and of course when the lamp is burned out, it is of no consequence that it would become broken on being removed from the socket.

What I claim as my invention is:

A safety lock for electrical lamps or bulbs comprising in combination a threaded sleeve, spring lingers secured to said sleeve with their free ends offset and extended inward toward the center of the threaded sleeve, 100 combined with a locking fragile flange on the threaded end of a lamp for cooperation with and movement between said lingers, said looking fragile flange being connected to the central Contact of the lamp and oper- In testimony whereof I ax my signature in the presence of two witnesses.

able to laterally displace said fingers as the JAMES WILLIAM DOVARD' 5 lamp is screwed into the socket said flange Wtnesess: being breakable and the ,central vconta-et VZACHARI-A'H DOWARD,

broken if the bulb is removed. THOMAS SMITH. 

